longclaps

любимые = [a, b, c]
нелюбимые = [d, e, f]
function menu(лимит){
    result = []
    while питательность(result) < лимит{
        if random() > 0.3 // число взято наобум
            продукт = случайный(любимые)
        else
            продукт = случайный(нелюбимые)
        if  продукт не в result
            добавить продукт в result
    }
    выбросить из result последнее
    return result
}

SELECT
  calendar.*,
  subjects.id,
  subjects.subject_name,
  teachers_users.full_name AS teach_name
FROM calendar
  JOIN subjects ON calendar.subject = subjects.id
  JOIN teachers_users ON subjects.subject_teacher = teachers_users.id
WHERE calendar.class = 1;

SELECT A.tovar_id FROM `таблица` AS A
                  JOIN `таблица` AS B
    ON A.tovar_id = B.tovar_id
    WHERE A.data = "data6" AND B.data = "data7";

SELECT SUM(1) FROM T; --  вернет число строк в непустой таблице, иначе - null

CREATE TABLE "T" (
	`action_ID`	INTEGER NOT NULL,
	`prov_title`	TEXT NOT NULL,
	`track_no`	TEXT NOT NULL
);
INSERT INTO `T` VALUES
 (10001,'ProvA','#12345'),
 (10001,'ProvB','AB123'),
 (10001,'ProvC','R-0001'),
 (10002,'ProvA','AC456'),
 (10002,'ProvB','R-0002'),
 (10002,'ProvC','#98765');

SELECT
  A.action_ID,
  A.track_no,
  B.track_no,
  C.track_no
FROM (SELECT * FROM T WHERE prov_title = "ProvA") AS A
JOIN (SELECT * FROM T WHERE prov_title = "ProvB") AS B
JOIN (SELECT * FROM T WHERE prov_title = "ProvC") AS C
ON A.action_ID = B.action_ID AND A.action_ID = C.action_ID;